The present invention generally pertains to cooling apparatus, and more particularly, but not by way of limitation, to cooling apparatus using “low profile extrusions”. As is explained in greater detail hereinbelow, such apparatus are extremely useful in printed circuit board (PCB) level cooling of electronic components, and for use as heat exchangers in applications where space is limited and/or low weight is critical. The present invention also pertains to an improved, high volume apparatus and method for manufacturing extruded hollow tubes for heat exchangers and heat pipes, including “low profile extrusions”.
As used in this document, the term “low profile extrusion” refers to a heat exchange apparatus comprising an integral piece of metal having a series of micro extruded hollow tubes formed therein for containing a fluid. The low profile extrusions preferably have multi-void micro extruded tubes designed to operate under the pressures and temperatures required by modern environmentally safe refrigeration gases and to resist corrosion.
The micro extruded tubes are preferably interconnected at their ends so as to provide fluid communication between each tube. Such low profile extrusions are preferably formed from aluminum, although other conventional metals or metal alloys may also be used. The micro tubes can have a diameter from about 0.0625 inches to about 0.5 inches, but can also have significantly smaller diameters.
Such low profile extrusions can currently be manufactured with a profile, or height, as low as about 0.05 inches and with tubes of varying inner diameters. Of course, future advances may allow such low profile extrusions to be manufactured with an even smaller profile. Such low profile extrusions have been conventionally used in heat exchanger applications in the automotive industry, and are commercially available in strip form (having a generally rectangular geometry) or coil form (a continuous strip coiled for efficient transport). Preferred low profile extrusions are sold by Thermalex, Inc. of Montgomery, Ala. A brochure entitled “Thermalex, Inc.—Setting A Higher Standard in Aluminum Extrusions” (hereinafter the “Thermalex Brochure”) provides additional detail regarding the Thermalex low profile extrusions and is incorporated herein by reference. U.S. Pat. No. 5,342,189, which is incorporated herein by reference, provides additional detail regarding an extrusion die for making such low profile extrusions. U.S. Pat. No. 5,353,639, which is incorporated herein by reference, provides additional detail regarding a method and apparatus for sizing a plurality of micro extruded tubes used in such low profile extrusions.